Abstract
An amphiphilic polymer, polyallylamine containing poly (L-alanine) hydrophobic graft chains, (PAAg-PAla), was prepared. The amphiphilic polymer was observed to form a monolayer at the air-water interface. The structure of the monolayer was found to be strongly pH dependent in aqueous solution. In acidic conditions, the protonated allylamine moieties of PAAgPAla dissolved readily into the aqueous phase, while the hydrophobic poly (L-alanine) graft chains acted as anchors to keep the monolayer at the interface, resulting in the formation of a collapsed monolayer. In alkaline conditions, the PAAgPAla chains were located entirely at the air-water interface, forming stable and closely-packed uniform monolayers owing to dehydration of the allylamine moieties. In the monolayer, the poly (L-alanine) graft chains self-assembled, owing to the loss of electrostatic repulsions between the neighboring allylamine moieties, yielding β-sheet structure domains at the interface. These active domains interact specifically with aqueous L-alanine rather than with its corresponding Disomer.
